7 folders cost $11.90. Which equation would help determine the cost of 10 folders?
There are several equations that could help determine the cost, each with a slightly different approach. If we let $x$ represent the cost of 10 folders, we have the following proportion: $\dfrac{x}{10}$ We have to pay $11.90 for 7 folders, and that can be written as a proportion: $\dfrac{\$11.90}{7}$ Since the price per folder stays the same, these two proportions are equivalent. $\dfrac{x}{10} = \dfrac{\$11.90}{7}$